Expansion unit to compensate for temperature changes in a vehicle hydraulic drive system



w. 'E. BEAMAN July 17, 1951- EXPANSION UNIT TO COMPENSATE FOR TEMPERATURE CHANGES IN A VEHICLE HYDRAULIC DRIVE SYSTEM Filed Jan. 28, 1946 3 Sheets-Sheet l I Ill/671107 Zdiliz'am .E. .Beamczrz By I! wwfi hg July 17 1951 w. E. BEAMAN 2,561,167

I EXPANSION UNIT TO COMPENSATE FOR TEMPERATURE CHANGES IN A VEHICLE HYDRAULIC DRIVE SYSTEM 3 Sheets-Sheet 2 Filed jaw. 28, 1946 III I nveutor William K Beamafi' rneys July 17, 195'] w. E. BEAMAN 2,561,167

EXPANSION UNIT TO COMPENSATE FOR TEMPERATURE CHANGES IN A VEHICLE HYDRAULIC DRIVE SYSTEM Filed Jan. 28, 1946 3 Sheets-Sheet 5 Inventor lzliiiiam E.Beaman Patented July 17, 1951 EXPANSION UNIT TO COMPENSATE FOR TEMPERATURE CHANGES IN A VEHICLE HYDRAULIC DRIVE SYSTEM William E. Beaman, Foresthill, Calif.

Application January 28, 1946, Serial No. 643,932

6 Claims. (Cl. 180-66) The present invention relates to new and useful improvements in drive means for motordriven vehicles or for any shaft used for driving machinery, a ships propeller or the like and more particularly to a combination hydraulic transmission, differential and braking system between a prime mover and a,driven element.

An important object of the present invention is to provide a mechanism of this character by means of which each of the four wheels of the vehicle are independently driven through the provision of a central hydraulic system.

A further object of the invention is to provide hydraulic drive means for the wheels of the vehicle and embodying means for reversing the drive thereof. I

A still further object is to provide an apparatus of this character of simple and practical construction, which is eflicient and reliable in operation, relatively inexpensive to manufacture and install in operative position on the vehicle and which otherwise is well adapted for the purposes for which the same is intended.

Other objects and advantages reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a top plan view.

Figure 2 is an end elevational view of a pair of the drive wheels and with parts of the vehicle frame broken away and shown in section.

Figure 3 is an enlarged sectional view of the drive unit for one of the wheels.

Figure 4 is a sectional view taken on a line 44 of Figure 3.

' Figure 5 is an enlarged sectional view of the gear pump and the slide valve control means for the forward, reverse and neutral passages leading from the intake and discharge sides of the pump.

Figure 6 is a sectional view taken substantially on a line 6-6 of Figure 5.

Figure 7 is a sectional view of the flexible drive shaft for one of the front wheels, and

Figure 8 is a detail of the expansion unit for the hydraulic system.

Referring now to the drawings in detail wherein for the purpose of illustration I have disclosed a preferred embodiment of the invention the numerals 5 and 6 designate the front wheels of a vehicle while the numerals 1 and 8 represent the rear wheels thereof. A power plant is shown at 9 which is of conventional construction, such as 2 an internal combustion engine, having its crank shaft l 0 extending from the rear end thereof into a gear pump housing I I also of conventional construction, the housing H having the pump gears l2 operatively mounted therein.

To each side of the housing II are secured the valve housings I3 and i4 communicating respectively with the intake and discharge sides of the pump by means of ports l5 and I6.

Spaced parallel passages l1, l8 and 19 are formed in the housing I 3 and similar passages Ila, l8a and Hot are formed in the housing [4 and communicate with the respective passages l5 and IS, the parallel passages in each valve housing being controlled respectively by slide valves 20 and 2| each having a port 22 arranged to open one of said parallel passages while the remaining passages are closed.

The passages I1 and Ila of the valve housings may be designated as forward fluid drive passages, the passages l8 and [8a being bypass passages extending between the two valve housings while the passages l9 and 19a represent the reverse drive fluid passages.

A pair of tanks 23 and 24 are included in the system, the passage I! being connected to the tank 23 by means of a pipe 25 and the passage 19a being also connected to the tank 23 by means of a pipe 26. The passage 19 is connected to the tank 24 by means of a pipe 21 and the passage Ila is also connected to the tank 24 by means of a pipe 28.

A pipe 29 leads from the front end of the tank 23 to the front wheel drive units 30 and 3| for the front wheels 5 and 6 respectively and a pipe 32 likewise leads from the front end of the tank 24 to said front drive units 30 and 3|.

A pipe 33 extends from the rear end of the tank 23 to the drive units 34 and 35 for the rear wheels 1 and 8 respectively and a pipe 36 likewise leads from the rear end of the tank 24 to the rear drive units.

Each of the drive units 30, 3|, 34 and 35 are of duplicate construction and accordingly a detailed explanation of one will suifice for all.

Each of said drive units is constructed in the form of a pump including annular motor chambers 31 and 38 separated by a partition 39. A drive shaft 40 is journaled in the partition 39 and projects outwardly through one side of the drive unit, the shaft having annular pistons 4| and 42 secured thereto for working in the respective chambers 31 and 38, the pistons being eccentrically mounted on the shaft and are offset in Figure 4. The intake and exhaust ports la-and- 46 are separated by means of a sliding abutment 45 working in each of the chambers and held against the periphery of the piston by coil:

springs 46.

The drive shaft 4!) constitutes the a-xleforone of the wheels such as shown at l, the axle-beingconstructed of inner and outer sections connected by universal joints ll and 48" to an inter mediate extensible axle section- 49,-the universal joints and the axle section ll] being enclosed within a ball and socket housing 50 and housing extensions 55a to provide for the independent movement ofthe'wheel when encountering a roadirregularity.

Thefront wheel construction as showninFigure 7- of the drawing is also provided with a universal joint 51 adjacenttheouter end of thedr-ive shaft -59 that is enclosed-within an outer ball and sockethousing 52- to provide for the steering of the front wheels;

In the operation of the device the gear pump 12 is constantly driven by theengine- 9 and when it is desired to place the drive system in its-neutralposition the slide valves- 20 and 21 are movedto registerthe-ports 22- thereof.- with the bypass paS- sages l8 and. [8a, the remaining passages in. the valve housings l3 and Hi thus being cut off;

When it is desired to; drive the vehicle forwardly the slide valves- 2% and 2 are moved into a position to open thepassages II and Ila whereby fluid will be pumped through the pipe 25 into the tank 23 and then movediforwardly and rearwardly through the pipes 29 and 33'to the front andrear drive units 39, 31, 34, and 35, the fluid being returnedv to the tank 2 3 by way of the pipes 32' and 36 as shown by the arrows in Figure 1 of the drawing.

When itis desired to reverse the drive the slide valves 20 and 21- are moved into a position to open the ports l and Mia whereby the direction of the flow through the tanks 23 and 21- as well as through the pipes leading from the front and rear end thereof will be reversed, and the drive units 35}, 3|, 3'4 and 35 at the front. and rear ends. of the vehicle will. be driven in a reverse direction.

In Figure 8 of the drawing, I have illustrated an expansionunit for the system to compensate for temperature changes and which comprises a plate 53 secured to a part of the frame A of the vehicle through which a square rod 54 is mounted for vertical sliding movement. Secured to the rod 5'4 is a lower plate 55 urged downwardly'aw'ay fromthe upper plate 53 by a leaf spring 56'.

Bellows members 5'3, 58 and 5'9: are-connected at their lower ends respectively to the pipes 25, IB' and 27 the bellows 5? and 59 being of equal size and all of'the bellows have their upper ends bearing against the plate 55 and these bellows are large enough to take care of the normal expansion and contractionof fluid inthe system for either he forward and reverse drives. The" bellows 58 for the by-pass passage is of a size proportional to either the bellows 5 F and 59', this proportion being equal to the proportion of fluid in the forward mechanism as compared to the fiui'd in the bypass. Thus the change in 4. bellows 58 would be equal in length to the change in length of either the bellows 51 or 59.

It will be apparent from the foregoing that by regulating the slide valves 20 and 2| the vehicle may be driven in either a forward or rearward direction and the individual drive units for the several wheels will provide a differential in the drive there'of. Likewise it will be apparent that abraking effect will be obtained, when it is desired, by the manipulation of the valves 20 and El into their forward and reverse positions.

It-is evident that the transmission is in operationat all-times either as a driving force or asa brake,- hencethe-- speed of the engine, at any given speed of the vehicle, must always remain the same. This will remain true whether the horsepower createdis used or not. The horsepower needed for a hill will be proportionately greater than the horsepower required for driving on a level road. Preferably a conventional form of. overdrive mechanism 60: isiinstalled between theengineS andpump- H? Inview otthe foregoing description taken in conjunction with the accompanying drawings itferre'd' embodiment of the invention the same: is

susceptible to certain changes fully comprehended by: the. spirit: of. the invention as herein described. and the scope oi the appended claims.

Having thus described the invention, what is claimed as new is;

I. In a hydraulic drive'for vehicles having a fiuid'd'rive. unit for each wheel and a closedfiuid system including. a motor operated pump con nected tosupply liquid pressure tothe drive units, control means at the inlet and outlet sides of the pump to reverse-the flow of fluid to said drive-units,- and/art expansion unitfor the system to compensate fortemperature changesof a liquid therein, said. expansion unit includ ing a plate fixed: to the vehicle, a rod slidably carried by the plate, a further plate fixed to the rod, spring means-spacing said plates, and bellows members carriedby the further plate and communicating'with one side of the pump;

2.- In a hydraulic drive for vehicles having a fluid drive unit for each wheel and aclosedfiuid' systemv including amotor operated pump connected to supply liquid pressure to the drive units, a pair of valve housings connected to the inlet and outlet sides of the pump and each having forward, reverse and bypass passages therein, means connecting said forward and reverse passages tothe drive units, a by-pass conduit connecting the by-pass passages of said valve housings, valves in said valve housings controlling the-fiow offluid through: said passages, and an expansion unit' for the system to compensate'for temperature changes, said'expansi'on unit communicating with one" side of the pump and including a plate'fixed to the vehicle, a rod slidably carried by the plate, a further plate fixed tothe rod; spring means spacing" said plates, and bel'low'smemb'ers'carried by the further plate and communicating with the by-pass conduit and said means connecting said forward and reverse passages to the drive units.

3. In a hydraulic drive for vehicles having a; fluid drive unit for each Wheel and a closed fluid system including a motor operated pump connected to supply liquid pressure to the drive units, a pair of valve housings connected to the inlet and outlet sides of the pump and having forward, reverse and by-pass passages therein, a pair of tanks, pipes connecting the forward and reverse passages of each valve housing to each tank, valves controlling the flow of liquid through said passages to reverse the flow of fluid to respective tanks, a by-pass condult connecting the by-pass passages, fluid connections from the tank to the drive units, and an expansion unit for the system to compensate for temperature changes, said expansion unit including a plate fixed to the vehicle, a rod slidably carried by the plate, a further plate fixed to the rod, spring means spacing said plates, a first bellows member connected to and communicating with the by-pass conduit, and further bellows members carried by the further plate and communicating with said pipes leading from one side of the pump.

4. In a hydraulic drive for vehicles having a fluid drive unit for each wheel and a closed fluid system including a motor operated pump connected to supply liquid pressure to the drive units, a pair of tanks connected direct to the respective drive units, forward and reverse passages connecting both the inlet and outlet sides of the pump to the respective tanks, valve means controlling the flow of liquid through said passages, and a fluid expansion unit for the system to compensate for temperature changes, said fluid expansion unit comprising an upper plate secured to a part of the vehicle, a rod slidably carried by said upper plate, a lower plate fixed to said rod, resilient means interposed between said plates and urging the lower plate from the upper plate, a group of bellows members depending from said lower plate and having lower ends connected to and in communication with said passages at one side of the pump.

5. In a hydraulic drive for vehicles having a fluid drive unit for each axle wheel and a closed fluid system including a motor operated pump connected to supply liquid pressure to the drive units; the improvement of which comprises an expansion unit for the system to compensate for temperature changes therein, said expansion unit including a plate fixed to the vehicle, a rod slidably carried by the plate, a further plate fixed 6 to the rod, resilient means interposed between said plates for spacing the further plate from the first named plate, and bellows members supported by the further plate and operatively connected to the system.

5. In a hydraulic drive for vehicles having a fluid drive unit for each wheel and a motor operated pump connected to supply liquid pressure to each drive unit, a valve unit having forward, reverse and by-pass passages therein communicating with one side of the pump, a pipe leading from the forward passage and connected to the drive units, a second pipe leading from the reverse passage and connected to the drive units, a by-pass pipe leading from the bypass passage to the other side of the pump, a valve in the valve unit for selectively opening one of the passages, and an expansion unit for the pipes to compensate for temperature changes of a liquid in the pipes, said expansion unit including a plate fixed to the vehicle, a rod slidably carried by the plate, a further plate fixed to the rod, spring means spacing the plates from each other, and a plurality of bellows members carried by said further plate and communicating with said pipes.

WILLIAM E. BEAMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 154,298 Teal Aug. 18, 1874 183,081 Thayer Oct. 10, 1876 806,759 Tuttle Dec. 5, 1905 873,819 Wing Dec. 17, 1907 958,212 Baab May 17, 1910 972,223 Pearson Oct. 11, 1910 1,099,161 Brown June 9, 1914 1,380,401 McQueen June 7, 1921 1,999,288 Fjellstedt Apr. 30, 1935 2,023,524 Heaton Dec. 10, 1935 2,228,411 Sheridan Jan. 14, 1941 FOREIGN PATENTS Number Country Date 618,899 France Dec. 23, 1926 636,922 Germany Oct. 17, 1936 776,645 France Nov. 8, 1934 

